垂穗披碱草居群穗部形态多样性研究

对采集自四川、西藏、甘肃、新疆、青海和内蒙古6个省(区)的29份垂穗披碱草的14项穗部性状进行多样性研究。结果表明,14项穗部形态性状的平均变异系数为27.34%,显示垂穗披碱草具有丰富的表型变异。居群总多样性指数H′为1.947,居群平均H′为1.424,则居群间H′为0.523。可见垂穗披碱草居群的遗传多样性主要集中在居群内部(73.14%),居群间的遗传变异较小(26.86%)。聚类分析,可分为种子大、较大、较小、小4种类型,较大居多。经主成分分析,其分布能解释总变异的86.63%,其中外稃长、第一颖芒长、穗宽、内稃长、小穗数、穗长等性状是影响较大的因素,这6个性状指标具有较高的特征向量值,基本可以揭示垂穗披碱草形态总体变异的趋势。垂穗披碱草多样性指数与海拔高度呈极显著正相关关系。     

放牧和刈割对草甸草原中小型土壤动物群落的影响

为了解放牧和刈割对草甸草原中小型土壤动物群落结构的影响,于2019~2020年在内蒙古呼伦贝尔市鄂温克旗贝加尔针茅草甸草原采用自由放牧、刈割和围封3种不同草地利用方式下,研究了内蒙古草甸草原中小型土壤动物群落结构特征。调查研究在草地返青期、生长期和枯黄期3个时期进行,共捕获中小型土壤动物284只,隶属于12目34个类群。结果表明:放牧导致中小型土壤动物数量、类群数和多样性指数降低,而刈割影响相对较轻;返青期、生长期、枯黄期对应的春、夏、秋三季中小型土壤动物群落结构存在明显差异,土壤动物个体数、类群数和多样性指数均在草地枯黄期最多。放牧和刈割利用方式下改变了草甸草原中小型土壤动物在草地生长期Shannon-Weiner指数、Margalef指数、Pielou指数的变化趋势。中小型土壤动物群落表聚性在刈割利用方式中表现最为典型,放牧利用方式下0~10 cm土层中小型土壤动物有向10~20 cm 土层移动趋势;土壤pH和速效钾含量与中小型土壤动物类群有密切关系。     

携带非典型cpb2基因牛源A型产气荚膜梭菌重组α毒素的免疫保护性研究

为验证重组α毒素对携带非典型cpb2基因的A型产气荚膜梭菌的免疫保护性,本研究应用PCR技术,从某牛场牛源A型产气荚膜梭菌G1分离株中扩增出1 194 bp的α毒素编码基因(cpa)和795 bp的β2毒素编码基因(cpb2)。经BLAST分析显示,G1分离株携带的cpb2基因与14个菌株的非典型cpb2基因的氨基酸序列同源性为95.1%～98.9%,与典型cpb2基因(L77695)的氨基酸序列同源性为61.7%。这表明,G1的cpb2基因为非典型cpb2基因。同时分别将cpa和cpb2基因扩增产物克隆于原核表达载体中,构建重组表达质粒pET-a和pET-b2,重组菌经IPTG诱导表达重组蛋白,将其纯化后单独及联合免疫小鼠进行免疫保护试验。结果显示,单独免疫重组α毒素蛋白组以及联合免疫重组β2毒素蛋白组的小鼠,均可以抵抗至少6倍最小致死量(MLD)的G1外毒素(包含α毒素和非典型β2毒素)的攻击,也可以完全抵抗至少6 MLD的G2外毒素(不包含β2毒素)的攻击。表明,重组α毒素蛋白对含有及不含有非典型β2毒素的A型产气荚膜梭菌均具有良好的免疫保护作用。     

Effect of Bovine Sperm‐Bound Antisperm Antibodies on Oviductal Binding Index

This study was designed to test the hypothesis that sperm‐bound IgG and IgA decrease binding of bull spermatozoa to oviductal epithelial cells in vitro. Three ejaculates were cryopreserved from each of four antisperm antibody (ASA)‐negative satisfactory breeder bulls. Bulls were then immunized with autologous spermatozoa, and three ASA‐positive ejaculates were cryopreserved from each bull post‐immunization. First, microscopy methods were compared to select the most appropriate assay for evaluation of oviductal binding index (BI). The BI did not differ when the evaluation was performed under fluorescence microscopy (131.1 sperm/mm²; 62.5–251.1 sperm/mm²), phase‐contrast microscopy (160.5 sperm/mm²; 56.8–397.4 mm²) or their combination (116.4 sperm/mm²; 56.8–249.6 sperm/mm²) (Median; IQR). The combination of microscopy methods was selected as it allowed better visualization of cells. Then, BI was compared between ASA‐negative and ASA‐positive ejaculates, and the association between BI and ASA binding was evaluated. The BI was less in ASA‐positive (114.9; 0 to 201.8 sperm/0.1 mm²) than ASA‐negative samples (218.9; 24.7 to 276.8 sperm/0.1 mm²) (P = 0.0002). This reduction in BI was significant in three of the four bulls. Regression analysis identified a negative association between BI and the percentage of IgG‐bound (p = 0.013) but not IgA‐bound spermatozoa. In conclusion, sperm‐bound IgG decreased the ability of bovine spermatozoa to bind to oviductal epithelial cells in vitro.     

不同施肥时间及施氮水平对高寒草甸生物量和土壤养分的影响

采用随机区组设计,探讨了不同施肥时期及氮肥用量对三江源区高寒草甸初级生产力、植物养分及土壤养分的影响。结果表明:在施肥时间为7月10日,施肥量为150 kg·hm^-2时,地上生物量为最大值,较对照增加了2.06倍(P <0.05)。而植物氮素含量在施肥时间为7月10日,尿素用量为300 kg·hm^-2时达到最大值,较对照增加了31.18%(P <0.05)。相关性分析表明,地上生物量与植物全氮成显著正相关,施氮量与植物全氮成线性相关。施肥时间为7月10日左右时,尿素施用水平为150~300 kg·hm^-2,该类型高寒草甸初级生产力和土壤全氮都达到最大值,可作为优先氮素添加量来推荐。     

营养舔砖对冷季放牧牦牛、藏羊的补饲效果

两个月的试验结果表明 ,补饲营养舔砖对维持牦牛和藏羊活重有明显作用。补饲营养舔砖牦牛试验组活重损失为 2 74kg ,而对照组为 8.8kg ,两者之间存在极显著差异 (P <0 0 1)。藏羊补饲营养舔砖试验组活重损失为 2 0kg ,而对照组为 5 .12kg ,两者之间差异显著 (P <0 0 5 )。     

Regrouping of pigs by body weight at weaning does not affect growth performance,carcass quality or uniformity at slaughter of heavy weight pigs

We studied the influence of pen uniformity at weaning (7.5 ± 0.6 kg vs. 7.5 ± 1.2 kg body weight (BW ± SD)) and sex on growth performance during the nursery (7.5 to 27.3 kg BW) and the fattening (27.1 to 130.5 kg BW) phases and carcass quality of barrows and castrated females (CF). During the nursery phase, pigs from the more uniform pens had lower feed efficiency (P = 0.05) than pigs from the less uniform pens. Also, barrows had higher average daily feed intake (ADFI) (P < 0.05) and average daily gain (P < 0.001) and better feed efficiency (P < 0.001) than CF. During the fattening phase, initial pen uniformity did not affect growth performance of the pigs but barrows tended (P = 0.08) to have higher ADFI and worse feed efficiency than CF. Trimmed primal cut yield tended to be higher for the more uniform pigs and better for barrows than for CF (P = 0.09). It is concluded that regrouping of the pigs at weaning according to uniformity of BW did not affect growth performance or carcass quality of the pigs at slaughter. Castrated females might be used as an alternative to barrows for the production of carcasses destined to the dry‐cured industry.     

牧草捆裹青贮技术的试验研究

牧草捆裹青贮是近年来在国外广泛推广和应用原一项青贮新技术。笔者着重对捆裹青贮的工艺,技术要求和配套机具进行了研究,并对捆裹青贮的草捆进行了质量综合分析评价。